U (disambiguation)

U is the twenty-first letter of the Latin alphabet.

U may also refer to:

Science

U, a common notation for potential energy
U, the middle of an edge joining a hexagonal and a square face of the Brillouin zone of a face-centered cubic lattice, in solid-state physics
U, one of the two subcarrier-modulated color-difference channels in the YUV colorspace, in video
U, the recommended symbol for a system's internal energy, in thermodynamics
U, units, any of various standard units of biological activity, such as insulin units, enzyme units, or penicillin units
- U, the enzyme unit
- International units, for which the symbol U is sometimes used
U, the abbreviation for selenocysteine, an uncommon amino acid containing selenium
u, the alternative abbreviation for the SI prefix "micro-" when the Greek letter mu (µ) is not available
U or U-value, the symbol for the overall heat transfer coefficient or thermal transmittance

An honorific used in Burmese names
An alternative spelling of Woo (Korean name), including a list of people with that family or given name
U of Goryeo (1363–1389), king of Goryeo (Korea), often called King Woo

U, Pohnpei, Federated States of Micronesia
Ü-Tsang, one of three historical provinces of Tibet
- Ü (region), a particular region of Ü-Tsang

/u/, the close back rounded vowel in the International Phonetic Alphabet
U language, a language spoken by about 40,000 people in the Yunnan Province of China
U (Cyrillic), a letter of the Cyrillic script
U (kana), a Japanese syllabary symbol
U and non-U English, sociolectal varieties of British English
Ս, glyph for the Romanian letter se
u, an abbreviation for "you" in computer chats
U-, a prefix used for German submarines during World War II
U, a title roughly equal to "Mister" in Burmese
The Greek letter μ

U (film), a 2006 French animated feature film directed by Serge Elissalde and Grégoire Solotareff
The U (film), a 2009 documentary about the Miami Hurricanes football team
U (Universal), a media content rating used in the following countries:
- United Kingdom, issued by the British Board of Film Classification
- India, issued by the Central Board of Film Certification
- Malaysia, issued by the Film Censorship Board of Malaysia
- France, documented at Censorship in France
- Latvia, Malaysia and Malta, documented at Motion picture content rating system and Television content rating system
U (TV channel), a former television channel in New Zealand
U, the production code for the 1965 Doctor Who serial The Myth Makers
The American Spanish-language network Univision has the U logo

U Mobile, Malaysian mobile phone and data service provider
U-bend, a U-shaped plumbing trap
U bolt, a U-shaped metal fastener
Ⓤ, (U inside a circle), hechsher or kosher certification by the Orthodox Union
U, symbol for Ustaše Croatian movement
Nickname for football teams:
- La U or Universitario de Deportes, Peru
- Universitatea Cluj, Romania
U, the color blue in Magic: The Gathering
Wii U, the sixth Nintendo video game home console, released in 2012
Uniform, the military time zone code for UTC−08:00
"U" Is for Undertow, the twenty-first novel in Sue Grafton's "Alphabet mystery" series, published in 2009